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- Committer: Anders Logg
- Date: 2008-05-15 16:02:44 UTC
- Revision ID: logg@simula.no-20080515160244-e2a4wkfxfzmts16s
Add new class SingularSolver:
This class provides a linear solver for singular linear systems
Ax = b where A has a one-dimensional null-space (kernel). This
may happen for example when solving Poisson's equation with
pure Neumann boundary conditions.
The solver attempts to create an extended non-singular system
by adding the constraint [1, 1, 1, ...]^T x = 0.
If an optional mass matrix M is supplied, the solver attempts
to create an extended non-singular system by adding the
constraint m^T x = 0 where m is the lumped mass matrix. This
corresponds to setting the average (integral) of the finite
element function with coefficients x to zero.
The solver makes not attempt to check that the null-space is
indeed one-dimensional. It is also assumed that the system
Ax = b retains its sparsity pattern between calls to solve().
This class provides a linear solver for singular linear systems
Ax = b where A has a one-dimensional null-space (kernel). This
may happen for example when solving Poisson's equation with
pure Neumann boundary conditions.
The solver attempts to create an extended non-singular system
by adding the constraint [1, 1, 1, ...]^T x = 0.
If an optional mass matrix M is supplied, the solver attempts
to create an extended non-singular system by adding the
constraint m^T x = 0 where m is the lumped mass matrix. This
corresponds to setting the average (integral) of the finite
element function with coefficients x to zero.
The solver makes not attempt to check that the null-space is
indeed one-dimensional. It is also assumed that the system
Ax = b retains its sparsity pattern between calls to solve().
- files added:
- dolfin/la/SingularSolver.cpp
- files modified:
- dolfin/fem/SparsityPatternBuilder.h
added
removed
dolfin/swig/dolfin_docstrings.i
